Add a MAXIMUM temperature setting.

In an office situation using the up/down setting to limit the maximum temperature is OK during standard working hours. However, out of hours (evenings & weekends) where we lower the temperature it then gives the problem that a person working out of hours can only raise the temperature by the range set in the up/down limit. If the up/down range is set with a wide range to accommodate this lower setting, it then gives the problem during working hours the temperature being allowed to be raised excessively.